1. Field of the Invention
The present invention relates to a vibration isolation unit, and relates specifically to a vibration isolation unit that can reduce the number of parts, man-hour and material cost, and can thereby suppress the product cost.
2. Description of the Related Art
As a vibration isolation unit preventing vibration of an engine for an automobile from being transmitted to a vehicle body while supporting and fixing the engine, one provided with a liquid-sealed vibration isolation device is known. In the vibration isolation unit, the liquid-sealed vibration isolation device is interposed between the engine and the vehicle body through an engine side bracket and a vehicle body side bracket.
For example, in Japanese Unexamined Patent Application Publication No. 2009-14080 (refer to FIG. 1 to FIG. 3, FIG. 14 to FIG. 16, paragraphs 0029, 0036 to 0038, and the like), an inverted type vibration isolation unit is disclosed in which a vibration isolation body 18 (liquid-sealed vibration isolation device) is configured such that a lower attaching tool 12 is attached to the vehicle body side through a frame-like second bracket 22 (vehicle body side bracket) of a rectangular shape in a front view and an upper attaching tool 14 is attached to the engine side through a first bracket 20 (engine side bracket) projecting sideways, in the vibration isolation body 18, the lower attaching tool 12 (boss member) and the upper attaching tool 14 (outer tube tubular part) are connected by a vibration isolation base body 16, and a liquid-sealed chamber 28 is formed between the isolation base body 16 and a diaphragm 30.
In the vibration isolation unit, as a stopper mechanism damping and restricting excessive relative displacement of the upper attaching tool 14 with respect to the lower attaching tool 12, a stopper rubber 84 is furnished in the first bracket 20. The stopper rubber 84 includes a first stopper rubber 86 arranged so as to cover the upper surface of the vibration isolation body 18 and opposing an upper wall 76 of the second bracket 22, and a second stopper rubber 88 extended downward from an edge of the first stopper rubber 86 and interposed between a tubular holding part 46 (pressed-in part) of the first bracket 20 and a vertical wall 74 (side wall) of the second bracket 22.
Also, at the lower end of the second stopper rubber 88, a fixing rubber piece 96 is extended inward in the radial direction, and the stopper rubber 84 is fixed without dropping and dislocation because the fixing rubber piece 96 is held between a flange 26 of the upper attaching tool 14 and a lower end 46c of the tubular holding part 46 of the first bracket 20.
However, the number of parts increases because the conventional vibration isolation unit described above is configured such that the stopper rubber 84 is vulcanizingly molded as a single body and is mounted so as to cover the first bracket 20. Also, in the manufacturing process of the vibration isolation unit, it is required to control to confirm that the fixing rubber piece 96 is properly held between the flange 26 and the tubular holding part 46, and therefore the man-hour increases. Further, rubber material is used inefficiently because a part of the first stopper rubber 86 covering the upper surface of the vibration isolation device body 18 overlaps with a part of the diaphragm 30 in an axial view. Thus, in the conventional vibration isolation unit, there is a problem that the number of parts, man-hour and material cost increase with provision of the stopper rubber, and the product cost increases as much.